Remote Sensing of Plastic Near the Surface Ocean: An Experimental Study

The ocean is an expansive but not limitless habitat accounting for 71% of the Earth’s surface. Plastic pollution in the ocean is a

growing ecological concern for pelagic ecosystems because of its slow degradation time and ability to absorb and concentrate

pollutants. Investigations into locating ocean plastic pollution have most commonly relied on limited in-situ collection and

modeling, but have been limited by their lack of quantitative data. Ocean remote sensing of plastic pollution has been attempted

with uncertain results due to (1) the lack of supportive in-situ data and (2) the limited spectral and spatial range for plastic at the

ocean’s surface. Garaba et al. (2018) found that utilizing peaks in the visible and near infrared (NIR) appear promising for

detecting plastic in hyperspectral data. This investigation examined four plastic types—ghost net, lids, bottles, and bags—

comprised of varying types of polyethylene in a preliminary study by obtaining visible and NIR optical data of these plastics at

varying depths in a swimming pool using a handheld spectral radiometer (ASD Fieldspec Handheld-2). Reflectance analysis

revealed plastic signal attenuates exponentially with depth and disappears after 50cm. As most ocean plastic resides in the

upper 50cm of the water column, it is possible that satellite imagery can discern plastic signals beyond the ocean’s surface. This

study examined the feasibility and also provides the framework for future algorithms to detect ocean plastic through remote

sensing.